350-501 Practice Test 13 — 15 Questions

Question 1

Which MEF Carrier Ethernet service type is used for a rooted-multipoint topology, where a single root site communicates with multiple leaf sites but leaf sites cannot communicate directly?

Accepted Answer

E-Tree. E-Tree (Ethernet Tree) is a rooted-multipoint service where the root can communicate with leaves, but leaves cannot communicate with each other.

Answer

E-Access

Answer

E-LAN

Answer

E-Line

Question 2

What is the main benefit of using Q-in-Q (802.1ad) in metro Ethernet networks?

Accepted Answer

Increases the number of available VLANs. Q-in-Q allows multiple customer VLANs to be encapsulated within a service provider VLAN, increasing scalability.

Answer

Simplifies routing

Answer

Provides encryption

Answer

Reduces latency

Question 3

In IOS XR, what is the commit/rollback configuration model?

Accepted Answer

Configuration changes are staged and committed atomically; rollback is supported.. The commit/rollback model applies changes atomically and allows reverting to previous configurations if needed.

Answer

It requires a reboot to apply changes.

Answer

Changes are applied immediately and cannot be undone.

Answer

It only applies to interface configurations.

Question 4

Which TWO access technologies are considered fiber-based solutions for service provider access networks? (Select two.)

Accepted Answer

XGS-PON. GPON and XGS-PON are fiber-based PON technologies.

Answer

WiMAX

Answer

Cable (DOCSIS)

Answer

DSL

Question 5

Which THREE of the following are benefits of using EVPN over traditional VPLS for L2VPN services? (Select three.)

Accepted Answer

Integrated L2 and L3 services (e.g., IRB). EVPN offers BGP control plane, multi-homing with ESI, and integrated L2/L3 services.

Answer

Supports only point-to-point pseudowires

Answer

Eliminates the need for VPLS

Question 6

Which Cisco SP router platform uses IOS XR and is commonly deployed at the aggregation layer, supporting both L2 and L3 services?

Accepted Answer

Cisco ASR 9000. Cisco ASR 9000 is an aggregation router running IOS XR, suitable for L2/L3 services.

Answer

Cisco CRS

Answer

Cisco ASR 1000

Answer

Cisco NCS 540

Question 7

A service provider wants to offer a point-to-point Layer 2 Ethernet service between two customer sites with strict SLAs. The solution must use MPLS pseudowires. Which MEF service type aligns with this requirement?

Accepted Answer

E-Line. E-Line is a point-to-point Ethernet service defined by MEF. E-LAN is multipoint, E-Tree is rooted multipoint, E-Access is for access to a service provider network.

Answer

E-Tree

Answer

E-Access

Answer

E-LAN

Question 8

In BGP/MPLS IP VPN (L3VPN), which component provides customer isolation by maintaining separate routing tables per customer?

Accepted Answer

VRF. VRF (Virtual Routing and Forwarding) creates separate routing tables for each customer, ensuring isolation.

Answer

Route distinguisher (RD)

Answer

MPLS label

Answer

MP-BGP

Question 9

A service provider is implementing EVPN to support multi-homing for a customer site. Which EVPN attribute ensures that only one of the PEs forwards traffic for a given Ethernet segment?

Accepted Answer

Designated Forwarder (DF) election. The ESI (Ethernet Segment Identifier) and designated forwarder election ensure single active forwarding per segment. DF election is used for multi-homing.

Answer

Label block

Answer

Route Target

Answer

Ethernet Tag ID

Question 10

In IOS XR, each routing protocol runs as a separate process. What is the primary benefit of this architecture?

Accepted Answer

It allows each protocol to be upgraded independently without a system reboot.. Process separation provides fault isolation; a crash in one protocol process does not affect others, improving overall system stability.

Answer

It simplifies configuration by combining all protocols into a single file.

Answer

It reduces memory consumption by sharing code between processes.

Answer

It improves forwarding performance by dedicating CPU cores to each protocol.

Question 11

Which architecture feature of IOS XR ensures that a failure in one routing protocol process does not affect other processes on the same router?

Accepted Answer

Process separation with each protocol as a separate process. IOS XR uses a distributed OS with process separation; each protocol runs as a separate process in its own memory space, providing fault isolation.

Answer

Admin plane vs default SDR

Answer

Commit/rollback configuration model

Answer

CPU and memory allocation per card

Question 12

A service provider is implementing network slicing for 5G services. Which of the following is NOT a typical characteristic of a network slice?

Accepted Answer

Slices require dedicated physical infrastructure per slice.. Network slices are isolated virtual networks, but they share the same physical infrastructure; they do not have dedicated physical links.

Answer

Each slice can have its own dedicated virtualized functions and resources.

Answer

Slices can be customized for specific service types like eMBB, uRLLC, or mMTC.

Answer

Slices are isolated from each other in terms of performance and security.

Question 13

Which Cisco router platform is designed for the core/backbone of a service provider network, supporting high-density 100GE interfaces and massive scale for MPLS and Segment Routing?

Accepted Answer

Cisco CRS. The Cisco CRS (Carrier Routing System) is a core router platform with high-density interfaces and large scale for MPLS and Segment Routing.

Answer

Cisco ASR 9000

Answer

Cisco ISR 4000

Answer

Cisco NCS 5500

Question 14

In IOS XR, each routing protocol runs as a separate process. What is the primary benefit of this architecture?

Accepted Answer

Fault isolation between protocols. Process separation prevents a failure in one protocol from affecting others, enhancing overall system stability.

Answer

Faster convergence by running protocols in parallel

Answer

Reduced memory usage by sharing libraries

Answer

Simplified configuration due to centralized processing

Question 15

Which TWO of the following are characteristics of the IOS XR operating system architecture? (Select two.)

Accepted Answer

Commit/rollback configuration model. IOS XR features a distributed OS and a commit/rollback configuration model.

Answer

Configuration changes take effect immediately without commit

Answer

Monolithic kernel where all processes share memory

Answer

All line cards run a single control plane process